On Tuesday morning, Mr. Trump had renewed his attacks on another critic in the Republican Party, Senator Bob Corker of Tennessee, saying he “couldn’t get elected dog catcher in Tennessee.” Mr. Corker, appearing more weary than angry, said the president “is debasing our country.”_________________Hiromichi

From my experience it means that anybody could be a dog catcher in Tennessee. No offence ment to dog catchers anywhere.

Tennessee has no relevance. It could be anywhere. To bring the comment down to basics, the meaning of the statement is that the person being spoken of, does not have either the skills or qualifications to win any elevtion.